Why? Because most of them do not understand how a vaccine works or how the vaccines protected millions of people from death. Of course, overly protective mothers (and along them a ton of bull-shit dads who would know better since you’d expect a man to be more logical in reasoning) have heard that vaccines are bad, that they create autism and other freaking stuff.
Vaccines work by injecting dead or inoffensive viruses or bacteria into your body. Yes, it infects you with dead microbes so that the immune system can analyze those dead microbes and then prepare protection accordingly.
Of course, vaccines do not work 100%, but they saved millions of people and have eradicated some diseases in parts of the world. But now diseases start to re-appear. Why? Because those very same mothers who refuse to vaccinate their kids are exposing everyone else to the illnesses.
Let’s learn about vaccines: